<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
    <style>
        .box{
            position: fixed;
            bottom: 50px;
            right: 50px;
            border: 1px solid red;
        }
    </style>
</head>
<body>
<div class="box">
    这里是小广告,啦啦啦
</div>

<img src="http://placekitten.com/1024/1024">

</body>
</html>